Recovery of bitumen by steam injection

Abstract

A method of recovering bitumen from a subterranean tar sand formation by the following multi-step method. First, an injection well is drilled to the formation and cased. Perforations are provided in the portion of the injection well contacting the formation. Next, a plurality of production wells are drilled and completed into the formation positioned above and along the length of the injection well. Thereafter, a heated fluid is circulated through the injection well contacting the formation via the perforations and thereby reducing the viscosity of the bitumen contained therein rendering same mobile. Subsequently, the mobilized bitumen is recovered through the plurality of production wells.

Therefore, we claim: 
     
       1. Method of recovering bitumen from a subterranean tar sand formation containing bitumen which comprises: drilling and completing an injection well to said formation and extending same into said formation, casing said injection well;   drilling and completing a plurality of production wells into said formation positioned above and along the length of said injection well;   perforating the portion of said cased injection well in contact with said formation, circulating a heated fluid through said injection well contacting said formation via said perforations and thereby reducing the viscosity of said bitumen contaned therein;   recovering said bitumen of reduced viscosity via said production wells.   
     
     
       2. The method of claim 1 wherin said injection well is extended into said formation near the bottom of same. 
     
     
       3. The method of claim 1 wherein said heated fluid is steam. 
     
     
       4. The method of claim 1 wherein said heated fluid is hot water. 
     
     
       5. The method of claim 1 wherein said heated fluid is circulated at a pressure to provide fluid communication between said injection well and production wells. 
     
     
       6. The method of claim 5 wherein subsequent to achieving said fluid communication, circulation of said heated fluid is stopped and said production wells are plugged back to a shallower depth in said formation and then circulation of heated fluid is resumed.